Compound air preheater for burners



March 6, 1934. T. J. ELLIS ET AL COMPOUND AIR PREHEATER FOR BURNERS Filed May 21, 1931 3 Sheets-Sheet 1 ll IH l HHHH Hl l l l UHl h l l l lHl l l lU I N VEN TORS A TTOA INV 'NTORS ATT RNEY 3 Sheets-Sheet 2 THOMHS Jmvss ELL/S fDWINf'REDtR/CKBURNS T J ELLIS ET AL COMPOUND AIR PREHEATER FOR BURNERS Filed May 21, 1951 March 6, 1934.

March 6, 1934. T. J. ELLIS ET AL 1,949,605

COMPOUND AIR PREHEATER FOR BURNERS Filed May 21, 1931 3 Sheets-Sheet 3 THO/4x75 JRMES ['1 M5 in wuv FEEDER] cx BuRNs IN V TORS BY /L ,"V

ATTO E Patented Mar. 6, 1934 UNITED STATES PATENT, OFFICE COMPOUND AIR PBEHEATER FOB BUBNEBS Thomas James Ellis and Edwin Frederick Burns, Gatineau, Quebec, Canada This invention relates to a compound air preheater for burners, of a type such as are used in the production of sulphurous or sulphuric acid.

The principal object of our invention is the El provision of acompound air pre-heater, in combination with a burner and combustion chamber unit, wherein primary air is pre-heated byheat radiation from the burner and secondary air is pre-heated by heat radiation from the combustion chamber.

Another object of our invention is the provision of a compound air pre-heater, in combination with a burner and combustion chamber unit, wherein the primary air to the intake end 1 of the burner is pre-heated by heat radiation from the burner and the secondary air to the intake duct of the combustion chamber is preheated by heat radiation from the combustion chamber.

9 Another object of our invention is the provision of a compound air pre-heater, in combination with a burner and combustion chamber unit, wherein the primary air is pre-heated by heat radiation from the burner; the secondary air is pre-heated by heat radiation from the combustion chamber; and embodying means whereby the primary pre-heated air may be utilized in the burner chamber and/or in the combustion chamber and means whereby the secondary pro-heated air may be utilized in the combustion chamber and/ or in the burner chamber.

Another object of our invention is to provide independent means for controlling the heated temperature of the primary and secondary air before entering the intake end of the burner and the intake duct of the combustion chamber respectively.

Another object of our invention is the provision of a compound air pre-heater for sulphur burners, which will increase the capacity of the burner, will increase gas concentration and obtain a maximum quantity of acid from the sulphur consumed.

Another object of our invention is the provision of a compound air-preheater for sulphur burners, which will eliminate the presence of sulphur trioxide and the danger of sublimation 50 in the gas coolers.

Another object of our invention is the provision of a compound air pre-heater for sulphur burners, which will maintain an even and high temperature in the burner and combustion cham- 55 her during operation.

Another object of our invention is the provision of a compound air pre-heater for sulphur burners, which permits the burner to be shut down for a reasonable length of time without danger of sulphur solidification and which may 00 be put into'operation within a minimum length of time. 7

With the foregoing and other objects in view as will appear as the description proceeds, the invention consists of the novel construction, com- 68 bination and arrangement of co-operating elements as hereinafter more specifically set forth claimed and shown in the annexed drawings forming a part of the present application, in which:

Fig. 1 is a side plan view of a burner and combustion chamber unit, with our compound air pre-heater shown in combination therewith.

Fig. 2 is a front end view of our burner casing and associate parts.

Fig. 3 is a sectional view of the closure casin and the associate portions of the discharge end of the burner and the inlet duct of the combustion chamber.

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 1, looking in the direction of the arrows.

Fig. 5 is a rear end view of our burner casing and associate parts.

Like numerals of reference designate corresponding parts throughout the diiferent views.

5 is a burner, having annular tracks 6 for rotatably mounting the same on trunnions 'l. 8 is a casing, enclosing around the burner 5 with the exception of an opening, at or near its rear end, through which atmospheric air enters the casing 8. To control the intake of primary air to the casing 8, I provide doors 9, which doors may be slidably supported on a suitable track 9 or they may be hinged to the respective sides of the rear end of the casing 8. The doors 9 have a semi-circular recess therein to snugly fit around the protruding end of the burner 5. The atmospheric air drawn into the casing 8 is pre-heated by heat radiation from the burner 5 and is drawn through the intake end 5a into the burner cham- 1 her of the burner 5, in the direction of the arrows Fig. 1. The forward end of the casing 8 is provided with an opening 10, which is preferably in alignment with the intake end 5a of the burner.

11 are suitable doors or closure members adapted 1 to close the opening 10. The supply pipe 12 conveys liquid sulphur from a melting kettle and discharges the same at a predetermined point internally of the burner 5. If dry sulphur is being burned instead of liquid sulphur, such dry 11 sulphur may be fed into the burner by a worn chute or in any other desired manner.

14 is a combustion chamber casing, which is suitably lined with flrebrick and provided with a transverse baflie-wall 15 in the combustion chamber 16. 17 is an intake duct, suitably connected to the combustion chamber casing 14 and in communication with the combustion chamber 16. The intake duct 17 is preferably in direct alignment and of a common size relative to the discharge end 5b of the burner 5. The adjacent ends of the intake duct 17 and the discharge end 512 are spaced apart to provide an air gap 18, as disclosed in Fig. 3, through which secondary air will enter with the products of burning, as they are discharged from the burner 5, through the intake duct 17 and into the combustion chamber 16.

19 is a casing, which encloses around the discharge and 5b of the burner and the adjacent end of the intake duct 17. The casing 19 is fixedly clamped on the intake duct 17, but is free from the discharge end 5b of the burner, to allow rotary motion thereof. The casing 19 may be provided with doors 19 to allow access to the interior from the opposite sides of the casing 19.

20 and 20' are casings extending around and in spaced relation from the combustion chamber casing 14. The casings 20 and 20 are closed at their top and bottom to provide air pre-heating chambers 20a and 20b between the combustion chamber casing 14 and the casings 20 and 20. 21 and 22 are C-shaped baflie plates, which are positioned between the combustion chamber casing 14 and the casings 20 and 20' respectively to convey the air in a. tortuous path of travel through the respective pre-heating chambers 20a and 20b. If desired, spiral bafile plates may be used instead of C-shaped baiiie plates. The heating chambers 20a and 20?) may be formed within the combustion chamber casing 14. 23 is an air inlet duct communicating with the pre-heating chamber 20a below the lower baflie plate 21. 23 is an air inlet duct communicating with the preheating chamber 20?) below the lower baflie plate 22.

24 is an air duct communicating from the preheating chamber 20a to the casing 19, for conveying a supply of secondary pre-heated air from the chamber 20a to the said casing 19. 24' is a cut-off damper for the air duct 24. The air duct 24 is provided with an ofiset air inlet 25. 26 is a damper slidably supported and adapted to close the air inlet 25 or the air duct 24. The damper 26, in its relation to the duct 24 and the inlet 25 is such that as one or the other is being closed by the damper 26, an equal proportion of the other will be opened. A constant pre-determined amount of air, either pre-heated, atmospheric or cool air or any assimilation thereof, will be drawn into the casing 19. If desirous, this damper 26 may be operated by a thermostat control. 27 is an air duct communicating from the pre-heating chamber 20b to the air duct 24. 27' is a cut-off damper for the air duct 27. Under certain conditions, sufiicient pre-heated air at a pre-determined temperature may be obtained through use of one or the other of the pre-heating chambers 20a or 20b, but under certain circumstances it may be desirous of obtaining a greater quantity of air or the same quantity of air at a higher temperature. If both dampers 24' and 27' are full open, a greater quantity of secondary preheated air may be obtained. If the dampers 24' and 27 are partially closed, the air drawn through the pro-heating chambers 20a and 20b will be retarded and the temperature of the secondary air will be increased.

28 is an air duct communicating at one end with the interior of the casing 8, adjacent the front end thereof, and at the-opposite end with the air duct 24. 29 is an air director carried under the roof portion of the casing 8 and slightly rearward of the intake end so of the burner. This air director 29 directs a portion of the top draught of the primary pre-heated air into the air duct 28. 30 is a damper suitably mounted at the joining point between the air duct 24 and the air duct 28 and which damper may be operated to close off the air duct 24 or the air duct 28. When the damper 30 is moved to close off the air duct 24, the primary pre-heated air from the interior of the casing 8 will be drawn through the air duct 28, air duct 24, casing 19, air gap 18, and the intake duct 17 into the combustion chamber 16. In certain cases, it may be desirous of assimilating a proportion of primary pre-heated air from the casing 8 and a proportion of secondary pre-heated air from the pro-heating chambers 20a.and 20b respectively or jointly. This may be accomplished by moving the damper 30 to intermediate position, to that of the positions hereinbefore referred to, and when in such position will permit secondary air through the air duct 24 and primary air through the air duct 28 to both be drawn and assimilate according to the variation of adjustment of the damper 30.

31 is an air duct connected to and in communication with the air duct 27. The other end of the air duct 31 is connected to the casing 18 and in communication with the interior thereof at a point forwardly of the intake end 57) of the burner. 32 is a damper suitably mounted at the joining point between the air duct 2'? and the air duct 31 and which damper may be operated to close ofi the air duct 27 or the air duct 31. When the damper 32 is moved to close ofi the air duct 27 and the damper 27' opened, the secondary air from the pre-heating chamber 20b will be drawn through the air duct 27, air duct 31 and into the casing 18, forwardly to the intake end 5b of the burner. When the secondary air is being drawn through the air ducts 24 and 27 to the casing 19, the dampers 30 and 32 will be operated to close the air ducts 28 and 31 respectively. When the secondary air is being drawn through only the air duct 24, the damper 32 may be operated to close the air duct 27.

Referring to Fig. 2, we provide air intake openings 33 in the casing 8, preferably at the front end. 34 are doors adapted to close the openings 33. In operation, it may be desirous to moderate the temperature of the primary pre-heated air by allowing atmospheric or cool air to enter the casing, preferably adjacent the intake end 5a of the burner. This is accomplished by admitting the atmospheric or cool air through the openings 33. If desired, these doors 34 may be operated by a thermostat control.

35 is a conduction pipe, adapted to convey the products of combustion to the gas coolers. This conduction pipe is provided with a vacuum fan, which draws the products of combustion off from the combustion chamber 16. The vacuum caused in the combustion chamber 16 will provide a suction draught of primary air and/or secondary air through the various ducts, as herelnbefore described, into the burner chamber or into the combustion chamber 16.

The best results and a maximum quantity of temperature relative to acid is obtained from the sulphur consumed when the primary pre-heated air, entering the intake end 5b of the burner, is of a predetermined temperature relative to the temperature in the burner chamber and when the secondary pre-heated air, entering the intake duct 17, is of a predetermined the temperature in the combustion chamber 16.

We do not wish that our compound air preheater, as disclosed in this application, be considered as limited to only the burning of sulphur to produce sulphurous or sulphuric acid, as a compound air preheater of the construction as disclosed in this application may be used for many other purposes.

The foregoing specification and annexed drawings disclose the preferred embodiments of our invention, but it is to be understood that minor changes may be resorted to in the commercial adaptation of our invention without departing from the scope of the invention as hereinafter claimed. I

What we claim as new is:

l. The combination with a unit, comprising a burner and a combustion chamber, of means for preheating supplies of air by heat radiation from said unit comprising an enclosure casing covering said burner and an enclosure casing around said combustion chamber; means for conducting preheated air from said first mentioned casing to said burner and to said combustion chamber and means for conducting preheated air from said second mentioned casing to said combustion chamber and to said burner.

2. The combination with a unit comprising a burner and a combustion chamber into which the incompletely burned gases from the former are discharged, or means for preheating supplies of air for said burner and for said combustion chamber by direct heat radiation from either member of said unit, means for feeding the heated air simultaneously to both members of said unit from said preheating means, and means whereby the supply of heated air from either of said preheating means may be wholly or partially cut of! when the supply of heated air from the other preheating means is being used.

3. The combination with a unit comprising a burner and a combustion chamber into which the incompletely burned gases from the former are discharged, of means for preheating supplies of air for said burner and for said combustion chamber by direct heat radiation from either member of said unit, means for feeding the heated air simultaneously to both members of said unit from said preheating means, means whereby the supply of heated air from either of said preheating means may be wholly or partially cut off when the supply of heated air from the other preheating means is being used, and controllable means for feeding air at atmospheric temperature into said incompletely burned gases while said gases are being discharged from said burner into said combustion chamber.

THOMAS JAMES ELLIS. EDWIN FREDERICK BURNS.

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